Rituxan Approved by FDA Against Rheumatoid Arthritis
In March of 2006, the U.S. Food and Drug Administration (FDA) approved the therapeutic antibody Rituxan (a.k.a. Rituximab), when taken in combination with methotrexate (MTX), to reduce signs and symptoms in adult patients suffering from moderately-to-severely active rheumatoid arthritis (RA). Rituxan is the first treatment for RA that selectively targets immune cells known as CD20-positive B-cells. Rituxan was approved after an intense Phase III trial.
Rituxan binds to a specific protein (the CD20 marker on the surface of the cell) that is found on the surface of some B-cells. From there, Rituxan works with the immune system to selectively deplete CD20-positive B cells. Through this unique mechanism of action, Rituxan may affect three pathways by which B-cells are believed to contribute to the initiation and development of RA. Rituxan does not target stem cells (B-cell progenitors) in the bone marrow, which lack the CD20 marker on the surface of the cells. Thus, B-cells can regenerate and gradually return to normal levels after treatment with Rituxan. Rituxan also does not target mature B-cells called plasma cells. In patients with RA, Rituxan is given as two 1000 mg IV infusions separated by two weeks, in combination with MTX. It is recommended to administer the steroid methylprednisolone 100 mg IV 30 minutes prior to each infusion. Rituxan is also used to treat cancer.
The FDA based its approval of Rituxan for RA therapy on the data produced by three randomized, double-blind, placebo-controlled studies of patients with active RA. Results of this Phase III trial, called REFLEX, showed that a significantly greater proportion of patients who received a single treatment course of two infusions of Rituxan with a stable dose of MTX achieved higher response rates compared to patients who received placebo and MTX. At 24 weeks, patients receiving Rituxan displayed clinically and statistically significant improvements in RA signs and symptoms, including pain and disability. The patient pool for this study included patients with active RA who had an inadequate response or were intolerant to prior treatment with one or more TNF antagonist therapies and current MTX therapy.
In REFLEX, the most frequent adverse effects recorded were primarily infusion-associated. Serious adverse events occurred in 7 percent of patients receiving Rituxan and MTX compared to 10 percent in patients receiving placebo and MTX. Less than 1 percent of acute infusion reactions were serious. The incidence of serious infections was 2 percent in Rituxan-treated patients and 1 percent in placebo-treated patients.
Article References
FDA Approves Rituxanš - The First Targeted B-Cell Therapy For Treatment Of Moderate-To-Severe Rheumatoid Arthritis, site accessed on 3/28/2006.
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